Thanks for the suggestion, I've just checked it and I think I may have found the setting, I wait and see if I still get as much activity after disabling it.
If you have no intention of running services available
to the net, make sure you are familiar with the router's
manual, so that you haven't enabled something you
ARP is a normal protocol though, would that be enough for firestarter to read it as a serious threat?
As for what's coming from the router itself, devices on a small
network are sometimes quite chatty, sending ARP broadcasts
and so forth.